In the related art, as a stylus including a bulb on the front end of a shaft, which has a diameter greater than a diameter of a shaft, a stylus disclosed in Japanese Patent No. 5567622 has been known. In the example of the related art, the stylus is formed by polishing and grinding in a state in which polycrystalline diamond is fixed to the front end of a shaft by brazing.
Here, the example, of the related art is described in detail with reference to FIG. 5. The stylus includes bulb 102 on the front end of shaft 101, which has a diameter greater than a diameter of shaft 101. In a configuration thereof, stainless steel is used for shaft 101 and polycrystalline diamond is used for bulb 102. In terms of processing of bulb 102, after a polygonal chip is fixed to shaft 101 by brazing with brazing filler material 31, polishing is performed and the front end portion is processed to have a bulb shape. Then, the processed portion and shaft 101 are again brazed with brazing filler material 31, polishing processing of the front end portion is repeatedly performed, and thereby, bulb 102 is formed on the front end of shaft 101. Further, shaft 101 has mortar shape 32 in order to fit to bulb 102 and is accurately positioned with respect to bulb 102. The example of the related art is described in more detail in Japanese Patent No. 5567622.